Fluorescence Lifetime Measurement Using Digital Time-Bin Segmentation
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Solution Overview
Problem
Current methods for measuring fluorescence lifetime are limited by long dead times and low measurement rates, resulting in incomplete data collection and prolonged time required to generate FLIM images.
Innovation Solution
A method and device that generate and process digital data sequences representing the temporal courses of excitation and detected light, allowing for the detection of photon events beyond the first photon arrival by translating analog signals into digital sequences at high sampling frequencies, enabling cyclic measurements at frequencies comparable to commercially available pulsed lasers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If commercial timing cards are used to detect photon arrival times, then measurement can begin, but the dead time becomes very long causing loss of subsequent photon information
Solution Approach 1:
The patent segments the detection process into multiple independent time bins within each excitation pulse period. Instead of using a single long dead-time card, the system divides the detection window into discrete time segments, allowing multiple photons to be detected and assigned to different time bins. This segmentation eliminates the information loss caused by long dead times in commercial cards.
2Measurement precision
If low measurement rates are used to avoid dead time limitations, then accurate timing is possible, but the time required to generate FLIM images becomes very long
Solution Approach 1:
The patent implements continuous measurement by processing multiple photons within each excitation pulse period without interrupting the measurement cycle. By using time-bin assignment and cumulative histogram building, the system maintains continuous data acquisition and processing, eliminating the need to wait for long dead times between measurements. This continuity dramatically increases productivity while preserving timing accuracy.
3Productivity
If high repetition rates of excitation pulses are used, then measurement speed increases, but the dead time prevents detection of subsequent photons
Solution Approach 1:
The patent employs periodic excitation pulses at high repetition rates and assigns detected photons to time bins within each pulse period. By systematically processing photons from multiple periodic cycles and accumulating histograms, the system achieves both high measurement rates and complete photon detection. The periodic structure allows efficient data organization and statistical convergence without dead time limitations.
4Device complexity
If only the first photon arrival is detected, then dead time constraints are satisfied, but significant measurement information remains hidden
Solution Approach 1:
The patent performs preliminary time-bin assignment for each detected photon as it arrives, rather than waiting for the end of the measurement period. By immediately recording the time bin for each photon and incrementing the appropriate histogram counter, the system captures complete temporal information without requiring complex post-processing or increasing hardware complexity. This preliminary action preserves all measurement information while maintaining system simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables more accurate and rapid data collection, significantly increasing the measurement rate and temporal resolution, allowing for the capture of nearly every photon event and reducing the time needed to generate FLIM images.
Implementation Method 1
By examining the lifetime of excited states in a sample labeled with one or more fluorescent dyes, important insights into the sample's properties can be gained.
Implementation Method 2
detecting the detection light emanating from the sample area with a detector as at least one photon event
Data Source
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AI summary
The method involves illuminating a sample region with an excitation pulse. A digital data sequence is generated, where the sequence is representative of a power-time profile of the pulse. A switching instant is determined from the sequence. A detection light (18) emanating from the region is detected by a detector (20). Another digital data sequence is generated, where the latter sequence is representative of a power-time profile of the detection light. Another switching instant is determined from the latter sequence, and a time difference between the two switching instants is calculated. An independent claim is also included for a device for measuring lifetime of an excited state in a sample.